1. Technical Field
The present invention relates to computers with an illuminator for a keyboard, and more particularly to battery-driven computers with a light source for illuminating a keyboard thereof.
2. Description of the Related Art
Portable computers are excellent in portability because they are small in size and light in weight, and can be used at any place independently of commercial power sources by mounting a battery charger in the interior. Generally, the portable computers are provided with a liquid crystal display (LCD), and many contrivances have been made in order to economize the consumption power of the battery. Since computers have generally been used in recent years at places remote from offices, there is an increasingly strong demand for using computers in a dark environment, for example, in an airplane or a living room. To use computers, there is a need for users to operate the keyboard and the pointing device while viewing the LCD. Because most LCDs are provided with a back light at the back side thereof, users can view the screen even if the surroundings are dark. However, since the keyboard and pointing device do not emit light unless they employ fluorescent paint or material, users cannot visually recognize a key position or a script on the key top in the dark and therefore users, other than an experienced person who can handle computers without relying on vision, cannot sufficiently use computers under such an environment. In addition, the back light of the LCD does not provide illumination enough to operate the keyboard.
Published Unexamined Japanese Utility Model Application No. 59-4493 discloses a technique of providing an illuminator in electronic equipment such as an electronic register and illuminating a keyboard thereof, as shown in FIG. 1. The illuminator is provided in the upper end of the front surface of the register, and when the register is used, the keyboard can be illuminated. This electronic register, however, is not a portable type but an installed type and is based on the assumption that commercial power sources can be utilized. In addition, the light source shown in FIG. 1 is considered to be an incandescent electric light. Furthermore, switching of the light source is realized only by manual operation of a switch installed in the illuminator.
Published Unexamined Japanese Patent Application No. 8-314598 discloses a technique of illuminating the keyboard of a personal computer (PC), as shown in FIG. 2. The light source is disposed between the keyboard and the display section and attached on the main body of the PC. In addition, the light source is partially covered so that light is not emitted to a place other than the keyboard. Furthermore, in the aforementioned specification No. 8-314598 it has been described that xe2x80x9cIn addition, when the light source is attached to the liquid crystal section, it becomes possible to visually recognize the keyboard in the dark place, but there is a problem that (1) a large-capacity light source is required, because the liquid crystal section and the keyboard are illuminated and (2) in the case of a liquid crystal section with a back light, light enters the liquid crystal and therefore disturbs the field of vision. Therefore, the aforementioned specification No. 8-314598 has taught that attaching the light source to the liquid crystal section has been given up because there is a problem from the viewpoint of both the capacity of the light source and the visual field with respect to the liquid crystal section.
Published Unexamined Japanese Utility Model Application No. 7-25415 discloses a technique of providing a detachable light source in a notebook-sized PC and illuminating the keyboard. In this publication, the light source is not attached to the main body of the PC and is provided as a separate unit.
As described supra, the portable computer is characterized in that it is excellent in portability. Therefore, in the case of providing a light source for illuminating the keyboard, it is important to select a method of attachment and an illuminator type so that the portability is not degraded. It is also important that an illuminator does not shorten the operating time of a battery.
The above-mentioned conventional techniques have shown the necessity of illuminating the keyboard of the portable computer. However, as described infra, it is difficult to adopt these techniques, while the characteristic of an actual portable computer is being utilized.
Published Unexamined Japanese Utility Model Application No. 7-25415 does not adopt the method of attaching an illuminator to the main body of the computer and adopts the detachable method. In this method, however, there is a need to carry the light source separately from the computer. Thus, this method cannot utilize the characteristic of the PC that is characterized by portability and also the operation of detachably attaching the light source will give users trouble.
In Published Unexamined Japanese Patent Application No. 8-314598, the light source is disposed between the keyboard and the LCD. Disposing the light source at this position, however, will cause some problems. First, in portable computers, a large area is used on this side of the keyboard in order to ensure the palm rest portion that holds the palms of a user when the user operates the keyboard. For this reason, in many cases it is difficult to ensure space for the light source at the position shown in FIG. 2. In addition, there is a need to make the light source higher than the plane of the key top of the keyboard and provide a cover, in order to illuminate the entire keyboard from the position of the light source shown in FIG. 2. For this reason, if an attempt is made to close the cover including the LCD, the computer will become considerably thick. Furthermore, because the entire keyboard is illuminated with the light source disposed at the position shown in FIG. 2, there is a need to provide a plurality of point light sources or an elongated light source and therefore a problem with the consumption power of the battery will arise.
The aforementioned Published Unexamined Japanese Utility Model Application No. 59-4493 discloses that the light source is disposed on the upper portion of the display section, but it does not disclose a specific idea for disposing the light source at the same position in a portable computer. Although this conventional technique discloses an idea for illuminating the keyboard with the light source disposed on the upper portion of the display section, there is no description of a specific method for disposing the light source on the upper portion of the LCD of a portable computer.
In addition, in any of the above-mentioned conventional techniques, there is no description of a specific method that switches on and off the light source, except for manual operation of the switch.
After all, the technique of illuminating the keyboard of a portable computer with a light source disposed on the upper portion of the LCD has hitherto been difficult and has not been realized. But, when the LCD is open in order to use the portable computer, there is no obstacle to intercept light between the upper portion of the LCD and the keyboard and therefore it follows that the upper portion of the LCD is most efficient as a position of illuminating the keyboard. However, since a distance from the light source to the keyboard becomes longer, it becomes important that an illuminator as a light source have a great luminous intensity and a lower energy consumption amount.
Furthermore, when the keyboard is illuminated from the upper portion of the LCD, there is a need to elaborate a plan so that the visual recognition of the LCD is not disturbed by direct light incident on the LCD. Moreover, it is useful that the ON-OFF state of a light source can be flexibly controlled as desired by users. Furthermore, it may be stated that it is practical from the standpoint of a reduction in power dissipation to control the ON-OFF state of a light source according to the system state.
In view of the above-mentioned facts, the primary object of the present invention is to provide a computer which is capable of being utilized even by battery-driven operation with less space and less consumption power and also realizing keyboard illumination capable of user""s flexible switching control without having an adverse effect on visual recognition of the display.
In accordance with a first aspect of the present invention, there is provided a computer with an illuminator for a keyboard capable of battery powered operation, having a keyboard, and a display comprising: an LED holder installed at approximately an upper edge of the display, the holder having a wall with an aperture; an LED installed inside the wall of the LED holder so that light radiated from the LED illuminates the keyboard by passing through the aperture; a switch to manually switch on or off the LED; and a switching controller circuit to control the switching of the LED in response to a signal from a main CPU mounted inside a main body of the computer or keyboard.
First, in the present invention, a light emitting diode (hereafter mentioned as LED) is selected as a light source for keyboard illumination. Generally, the LED has been used in displaying the operating state of electronic equipment and has been used as a device for displaying states rather than as a device for illumination. However, since LEDs with a relatively high luminous intensity suitable for illumination have been developed in recent years, the inventor of this application is led to an idea of applying the LED to the illumination of the keyboard of a portable computer to solve the problems not solved in the background art. The LED is suitable as an illuminator for a keyboard to be mounted on a battery drivable computer, because it is small, low in consumption power, and does not almost shorten the operating time of a battery.
In addition, an LED holder is attached to substantially the upper edge of a display and an LED is held within the LED holder. This position is most suitable as a place for attaching a light source because there is no obstacle with respect to keyboard illumination. In addition, by disposing a light source here, only a single point light source can illuminate the entire keyboard and there is no need to prepare a plurality of point light sources, a line light source, or a surface light source. The wall of the LED holder is formed with an aperture, and light from this LED is passed through the aperture and guided to the keyboard. The distribution of the light passed through the aperture can be controlled by adjusting the position at which the LED holder is attached and also the size and position of the aperture in the wall of the LED holder.
In addition, since the computer according to the present invention is equipped with the switch for manually switching on or off the LED, users can illuminate the keyboard as needed, by operating this switch.
Furthermore, because the computer is equipped with the switching controller circuit, switching of the LED is realizable not only by manual operation of the aforementioned switch but also by transmitting a signal, which instructs switching of the LED, from the main CPU mounted inside the main body of the computer or keyboard to the switching controller circuit.
In accordance with a second aspect of the present invention, a part of the light radiated from the LED is masked by the wall of the LED holder, and the remaining light passing through the aperture does not directly illuminate the display. This is realizable by suitably selecting, for example, the configuration of the holder, the attached position of the holder, the position of the aperture, the size of the aperture, and the like. Therefore, the second form of the present invention has solved the problem that when a light source is provided in the upper portion of the display, light radiated from the light source will disturb the visual recognition of the display, such as the problem pointed out in the background art.
In accordance with a third aspect of the present invention, when an angle formed by the display and the keyboard is at approximately 90 degrees, light from the LED passes through the aperture so that it illuminates substantially the keyboard alone. The angle of approximately 90 degrees is considered to be the smallest angle when users use the computer. If the entire keyboard is illuminated at this angle, the illumination of the keyboard is sufficiently ensured even when the angle formed by the display and the keyboard is greater than 90 degrees. As with the second embodiment, this is also realizable by suitably selecting, for example, a parameter related to the aperture.
In accordance with a fourth aspect of the present invention, the LED holder is provided with a shutter that adjusts the opening degree of the aperture. Therefore, the user can adjust light distribution in accordance with the inclined state of the display by manually adjusts the position of the shutter.
In accordance with a fifth aspect of the present invention, the switching controller circuit can be constructed to include at least either a keyboard controller to perform discrimination of depressed keys of the keyboard or a power source controller to control power to the entire system in response to an instruction signal from the main CPU. Since the switching controller circuit includes at least either the keyboard controller or the power source controller, the LED can be easily switched on or off in interlock with the control function of the keyboard controller or power source controller.
In accordance with a sixth aspect of the present invention, there is provided a portable computer with an illuminator for a keyboard capable of battery powered operation, having a main body with a keyboard on its upper surface, a back cover capable of being open and closed connected at a lower edge thereof to approximately a rear edge of the main body, and a liquid crystal display installed in the back cover, the portable computer comprising: an LED holder installed at approximately the center of approximately an upper edge of the back cover, the holder having a wall with an aperture; an LED installed inside the wall of the LED holder so that light radiated from the LED illuminates the keyboard by passing through the aperture; and a switching circuit constituted by connecting in series a cover switch which is switched on or off according to an open or closed state of the back cover and a manual switch which manually switches on or off the LED, the switching circuit be connected in series to the LED. In portable computers with a liquid crystal display (hereinafter referred to as an LCD), there are a great number of cases requiring keyboard illumination, compared with installation type. Accordingly, the present invention is particularly effective.
In addition, since the aforementioned switching controller circuit is connected in series with the LED, it is possible to switch on or off the LED by the cover switch as well as by the manual switch. That is, the cover switch is switched off if the back cover is closed. Therefore, the LED can be switched off without switching off the manual switch. As a result, even if the back cover is closed without switching off the LED, wasteful power consumption can be prevented.
In accordance with a seventh aspect of the present invention, the portable computer with an illumination for a keyboard having the sixth aspect further comprises: a switching element connected in parallel with the manual switch; and a control circuit to switch on or off the switching element according to a signal from a main central processing unit mounted inside the main body, or from the keyboard. As the switching element, a field effect transistor (hereinafter referred to as a FET) can be selected. Since the switching element is connected in parallel with the manual switch, the LED can be switched on or off by switching on or off the switching element by the control circuit, without operating the manual switch.
The control circuit can be configured by including at least either a keyboard controller mounted inside the main body for performing discrimination of depressed keys of the keyboard, or a power source controller to control power to the entire system in response to an instruction signal from the main central processing unit. Because the control circuit includes at least either the keyboard controller or the power source controller, the LED can be easily switched on or off in interlock with the control function of the keyboard controller or power source controller.